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C. L. STICKNEY..

EXPANSION DRILL. APP.ICAT|0N FILED NOV. 12. l9l8.

Patented J my 22, I919.

CHABL i L. STICKNEY, 0F SKULL VALLEY, ARIZONA,

EXPANSION-DRILL.

Specification of Letters Patent.

Patented July '22, illllld.

Application filed November 12, 1918. Serial No. 262,179.

To all whom it may concern:

Be it known thatI, CHARLES L. STICKNEY,

a citizen of the United States, residing at Skull Valley,in the" county of Yavapai and State of Arizona, have invented certain new and useful Improvements in Expansion Drills, of which the following is a specification.

This invention comprehends generally improvements in that class of inventions known as earth boring and drilling and more particularly has reference to an expansion drill.

It is a well known fact that in drilling or chambering shafts and tunnels that a small shaft is first provided and powder is generally placed in the bottom of this small shaft and fired for breaking away the surrounding ground for ore. However, it has often been found to be the case that when the powder has been fired about a foot or more of the small shaft at the bottom is untouched. It is the principal object and aim of the present invention therefore to provide a device of the above mentioned character designed to enlarge the bottom of the small shaft to provide a pocket so that powder may be placed therein and fired or exploded for effectively breaking away the surrounding ground or ore directly from the pocket or bottom of the small shaft.

More particularly this invention embraces the provision of a device of the above mentioned character wherein the mandrel or stock and the cutting jaws are of novel conformation and are designed to cooperate with each other during the operation of the mandrel for insuring of an extending and retracting of the cutters.

An additional and equally important object of this invention consists in the pro-' vision of a device of the above mentioned character wherein the stock or mandrel is bifurcated forming a recess, the lateral walls of which are inclined and formed with a stop against which the upper ends of the cutters contact so as to be extended.

It is a further object of this invention to provide a device of the above mentioned character wherein the cutters are of novel configuration and are slidably mounted between the jaws in the mandrel, and are also arranged for swinging movement into an extended position when the mandrel reaches the lowermost point of its downward stroke while in addition the jaws are so constructed and mounted that they are gravity operable,

that is, they automatically return to retracted positions during the upward stroke of the mandrel, thereby assuring of an efficient operation of the device in its entirety.

Among the other aims and objects of the present invention may be recited the provision of a device of the above mentioned character wherein the number of parts are comparatively few, the construction simple, the cost of production low, and the efliciency higlh. I

he improvements in the details and ar rangement of parts will be apparent from an inspection of the accompanying drawings, in connection with the specific description hereinafter contained, and wherein the preferred embodiment of the invention is disclosed for the purpose of" imparting a full understanding of the invention.

The invention is clearly illustrated in the accompanying drawings, in which:

Figure 1 is a side elevation of the improved device, the cutters being shown in an extended position,

Fig. 2 is a. vertical sectional view of the de vice,

Fig. 3 is a side elevational view of the device, the cutters being showntin a retracted or inactive position,

Fig. 4: is a bottom plan view of the device, the cutters being shown in extended position, and

Fig. 5 is a bottom plan view of the device, the cutters being shown in a retracted or inactive position.

Similar characters of reference are employed in all of the above described views, to indicate corresponding parts.

Referring now, more particularly, to the accompanying drawings there is provided a mandrel or stock 1 the lower end of which is bifurcated to provide spaced jaws 2, the space between which constitutes a recess 3 while the lateral walls of this recess are inclined as at 4 toward each other and are slightly curved at their inner, ends as at 5 so as to converge into a stop 6 which is positioned between the lateral walls as indicated. The jaws are formed with opposed longitudinal central slots 7 approximately medially of the ends for a purpose which will presently appear.

A pair of cutters generally designated by the numerals 8 and 9 are now provided and have their outer c-ids enlarged as at 10 and cut correspondingly and diagonally from the inner edges toward the' outer edges as indicated by the numeral 11. The diagonal and straight outer side edges of these cutters are sharpened as at 12 and 13 respectively so that when in use an effective cutting or breaking away of the ground at the bottom of a small shaft, not shown, will be effected, as is apparent. The outer portions of the cutters taper as at 14 correspondingly from the outer straight side edges to the inner edges to permit of the overlapping and arranging of the cutters in a retracted position in a manner which will hereinafter become apparent. Laterally extending cars 15 are formed on the inner edges of these cutters near the upper ends thereof while tangs 16 having rounded upper edges 17 are formed integral with the upper ends of the cutters and have their outer Side edges 18 arranged in substantial alinement with the outer straight side edges of the cutters while the inner edges 19 are inclined correspondingly toward each other for a purpose that will hereinafter appear.

In mounting the cutters between the jaws 2 the cutters are arranged side-by-side or in partial overlapping relation with each other as indicated in the drawings while a pivot pin 20 is engaged through the alining cars 15 and also slidably arranged in the alining slots 7 and this acts as a means for pivotally and slidably mounting the cutters in the recess. A suitable fastener such as a rivet 21 is passed through the jaws near the outer ends thereof and medially of the side edges serving as a brace for the jaws to increase the rigidity thereof while the inner edges of the cutters are provided with opposed recesses 22 for embracing the rivet and permitting of the cutters being arranged in a closed or retracted position.

The body of the mandrel or stock above the bifurcation is formed with a vertical bore 23 having laterally extending and in clined branches 24 which open at the outer edge of the mandrel and thereby forms a drain so that water will pass therethrough when the device is in use.

In using the present device, the cutters are normally arranged in a depending and partially overlapping position between the jaws and practically in alinement with the opposite side edges of the jaws, the supporting pin 20 resting at the lower ends of the slots 7, the peculiar shape of the cutters insuring of the same acting as weights so that they will be self centering and will of course lie in a retracted position normally or at least during the upward stroke of the mandrel. When the mandrel is partially rotated in the customary manner and moved on its downward "stroke, at the time the lower ends of the cutters strike the bottom of the small shaft, (not shown) these cutters will slide upwardly until the rounded upper edges 17 of the tangs 16 strike the inclined lateral walls 4 whereupon the rounded edges of the tangs will ride upon these inclined walls and during this movement the cutters will swing outwardly in opposite directions and of course about their pivots 20 until the inclined inner edges 19 of thetangsabut each other and until the rounded edges 17 strike the stop 6 which occurs simultaneously for limiting the expanding or the extending of the cutters. Owing to the sharpened edges 12 and 13 of the cutters it is apparent that when extended and when the mandrel operates in the usual manner, a pocket (not shown) will be provided at the bottom of the small shaft. It is to be understood of course that the pocket referred to is provided by a continuous operation of the device wherein the cutters are efiectively and alternately extended and retracted.

It is believed in View of the foregoing descriptionithat a further detailed description of the operation of the invention is entirely unnecessary. Likewise it is believed that the advantages of the invention will be apparent. v

Still further embodiments of the invention than those herein especially defined may be resorted to as conditions or preference may dictate, in keeping with the hereto appended claims.

-Having thus fully described this invention, what is claimed as new and desired to be secured by Letters Patent, is:

1. The combination with a mandrel bifurcated to provide spaced jaws and a recess the lateral walls'of which are inclined toward each other and slightly curved at their inner ends, and a stop formed medially of the inclined walls, of a pair of cutters pivotally and slidably mounted between-the jaws and having the upper ends designed to abut and ride upon the inclined and curved walls of the recesses when the cutters are moved upwardly to insure of the extending 110 of the cutters, the inner edges of the upper portions of the cutters being designed to abut each other at the timc'they abut the stop for limiting the extension of ,the cutters, and the cutters being shaped and 115 mounted to act as weights so that they will automatically assume a retracted position at times.

.2. The combination with a mandrel bifurcated to provide spaced jaws and a recess 120 the lateral walls of which are inclined correspondingly toward each other and slightly curved at their-inner ends, a stop formed between the walls, jand the jaws being formed with opposed longitudinal slots, of 125 a pair of cutters the outer portions ofwhich are tapered toward each other correspondingly while the outer portions are also G11, larged and cut diagonally from the inner edges to the outer straight edges, the diagonal and straight edges being sharpened; lateral ears formed on the adjacent inner edges of the cutters near the upper ends,

' the cutters being arranged side-by-side positioned between the jaws, a p1vot pin engaged through the opposed slots in the jaws and also engaging the ears for pivotally and slidably mounting the cutters, on the upper ends of the jaws and having their adjacent inner faces inclined relative to each other and having rounded and designed to abut and ride upon the inclined walls of the recess When the cutters are moved upwardly to insure the time the upper tangs formed.

their upper ends CHARLES L. STICKNEY. 

